package com.rabbitmq.demon.topics;

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;

import java.io.IOException;

/**
 * @author gavinli on 2017/10/9 下午1:21
 *         使用场景：发送端不只按固定的routing key发送消息，而是按字符串“匹配”发送，接收端同样如此。
 *         <p>
 *         1、exchange的type为topic
 *         <p>
 *         2、发送消息的routing key不是固定的单词，而是匹配字符串，如"*.lu.#"，*匹配一个单词，#匹配0个或多个单词。
 */
public class EmitLogsTopic {
    private static final String EXCHANGE_NAME = "topic_logs";

    public static void main(String[] args) {
        Connection connection = null;

        Channel channel = null;

        try {
            ConnectionFactory factory = new ConnectionFactory();
            factory.setHost("localhost");

            connection = factory.newConnection();
            channel = connection.createChannel();

            channel.exchangeDeclare(EXCHANGE_NAME, "topic");

            String routingKey = getRouting(args);
            String message = getMessage(args);

            channel.basicPublish(EXCHANGE_NAME, routingKey, null, message.getBytes());
            System.out.println(" [x] Sent '" + routingKey + "':'" + message + "'");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (connection != null) {
                try {
                    connection.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    private static String getRouting(String[] strings) {
        if (strings.length < 1) {
            return "anonymous.info";
        }
        return strings[0];
    }

    private static String getMessage(String[] strings) {
        if (strings.length < 2)
            return "Hello World!";
        return joinStrings(strings, " ", 1);
    }

    private static String joinStrings(String[] strings, String delimiter, int startIndex) {
        int length = strings.length;
        if (length == 0) return "";
        if (length < startIndex) return "";
        StringBuilder words = new StringBuilder(strings[startIndex]);
        for (int i = startIndex + 1; i < length; i++) {
            words.append(delimiter).append(strings[i]);
        }
        return words.toString();
    }

}